Directional Architecture in Tensegrity Systems: Towards ‘Bone & Muscle’ Metamaterials

在过去的十年里，机械超材料领域取得了巨大的进步，首要目标是创造新一代多功能和自适应的高性能材料。虽然表现出了突出的个人特性(例如超强纳米晶格、变形折纸结构)，但由于根本不同的设计原则，这些特性在很大程度上是不相容的。到目前为止，如何在机械超材料中协同实现真正的多功能还没有一个整体的概念。生物承重结构，如骨骼和肌肉生理学，基于所谓的拉伸完整性或张拉整体结构，独特地结合了有效的材料利用和适应各种多功能任务的能力。与已建立的超材料体系结构不同，十段结构由相互隔离的不连续压缩构件组成，并且仅通过连续的拉伸构件网络连接。尽管它们在机械上具有独特的拓扑结构，但作为超材料设计范式，10个部分尚未被探索；艾美诺太组旨在改变这一点-受生物骨骼和肌肉生理学的启发，这个艾美诺太组将张拉整体原则和定向材料、结构和功能设计结合成一种新型多功能张拉整体超材料的建筑概念。从蜂窝无与伦比的压缩稳定性到碳纳米管的极端导电性，在不同学科和不同尺度上，引人注目的物理特性依赖于高度定向效应和低维结构。提出的概念提供了一种跨学科适用的方法，它利用张量积分原理使这些效应可以在体积超材料中获得。特别是，这项建议的工作计划侧重于开发纳米和微米十段，这些纳米和微段由聚合物3D打印并裂解成陶瓷。因此，张拉整体载荷传递机制将利用热解收缩效应，通过受控的超高系索应变来诱导定向材料的微观结构可裁剪。这有望提供一条途径，利用极端取向和尺寸相关的材料特性，包括碳纳米管一样的强度和硬度。同时，对系绳张力和弹性杆屈曲机制的控制有望利用这种本质上易碎的组成材料实现广泛的稳定可逆变形能力。在此基础上，建筑概念将在随后的努力中扩展到结构和功能规模，其中可以采用纤维驱动原理来设计系绳，因为人工肌肉和压杆可以模仿动物骨骼等自然细胞层次结构。

The field of mechanical metamaterials has over the last decade seen dramatic progress, with the overarching goal to create a new generation of multifunctional and adaptive high-performance materials. Having demonstrated outstanding individual properties (e.g. ultra-strong nanolattices, shape-morphing origami structures), those characteristics are however largely incompatible due to fundamentally different design principles. To this day, there is no holistic concept how to synergetically implement true multifunctionality in mechanical metamaterials. Biological load-bearing structures, like bone-and-muscle physiologies, are based on so-called tensile-integrity, or tensegrity architectures and uniquely combine efficient material utilization with the ability to accommodate a broad variety of multifunctional tasks. In contrast to established metamaterial architectures, tensegrities are comprised of discontinuous compression members that are isolated from each other and only connected through a continuous network of tension members. Despite their mechanically unique topology, tensegrities have yet to be explored as metamaterial designs paradigm; the Emmy-Noether-Group aims to change thisInspired by biological bone-and-muscle physiologies, this Emmy-Noether-Group coalesces tensegrity principles and directional material, structure, and function designs into an architecture concept for a novel class of multifunctional tensegrity metamaterials. Across disciplines and scales, striking physical characteristics rely on highly directional effects and low-dimensional structures - from the unrivaled compressive stability of honeycombs to the extreme conductivity of carbon nanotubes. The presented concept provides an interdisciplinarily applicable approach that utilizes tensegrity principles to make these effects accessible in a volumetric metamaterial. In particular, the work program of this proposal focuses on the development of nano- and micro-tensegrities which are 3D-printed from polymer and pyrolyzed into ceramics. Thereby, tensegrity load-transfer mechanisms shall exploit pyrolysis contraction effects to induce directional material microstructure tailorability via controlled ultra-high tether straining. This is anticipated to provide a pathway to exploit extreme orientation- and size-dependent material properties, including CNT-like strength and stiffness. Simultaneously, control of tether straining and elastic bar buckling mechanisms are anticipated to program a wide range of stable reversible deformability with the intrinsically brittle constituent material. Based on that, the architecture concept will in subsequent efforts be expanded to the structure and function scale, where fiber actuation principles may be adopted to design tethers as artificial muscles and compressive bars could be modeled after natural cellular hierarchies like animal bones.